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Ferrule Type | Temperature Limit | Typical Uses | Advantages | Disadvantages |
---|---|---|---|---|
Graphite (100%) | 450°C | General purpose for capillary column connections to inlets and detectors |
Easy to use, can be tightened to hold column in place without seizing, column can be readjusted Can be removed easily High temperature limit Most forgiving of connection imperfections Can be re-used |
Allows air diffusion. Not for MS or oxygen-sensitive detectors Over tightening can extrude graphite into inlet or detector. Pieces flake off and stay behind, causing peak tailing and sample losses Soft, easily deformed or destroyed Interacts with solvent, causing tailing |
Vespel/Graphite | 400°C |
General purpose for capillary and packed glass columns Recommended MS or oxygen-sensitive detectors Reliable, leak-free connection |
Easy reliable connections Reusable & Remakeable Maintains shape, does not flake off Fairly forgiving of connection imperfections |
Design specific to fitting Shrinks with temperature cycling. Must re-tighten frequently Seizes on column, cannot be re-adjusted, must be cut off |
Vespel | 350°C |
Isothermal operation Reliable seals even with flawed surfaces, forms to sealing surface Excellent sealing material when making metal or glass connections Excellent for external connections |
Easy reliable connections Reusable & Remakeable Can be removed easily if used at room temperature Low air permeability |
Can shrink at elevated temperatures, must re-tighten frequently Can glue connections together if exceeding recommended temperature limit and destroy fitting |
Teflon | 250°C |
External connections not involving carrier gas Valve actuator gas lines Glass packed columns used at low temperatures |
Easy connections Can be re-used Very forgiving of connection imperfections Can seal with very little pressure |
Allows air diffusion. Not for MS or oxygen-sensitive detectors |